Trains are commonly used as an efficient means for hauling cargo and/or passengers over long distances. A typical train includes a plurality of non-powered rail cars and a plurality of locomotives for moving the non-powered rail cars along a track. Two or more locomotives grouped or otherwise controlled together for traction purposes are commonly referred to as a “consist.” Distributed power train operation involves controlling the supply of motive power produced by a lead locomotive (or lead consist) and one or more remote locomotives (or consists) that may be spaced apart from the lead locomotive and distributed throughout the train. Each locomotive of the train may be equipped with a communication system for providing wireless communications. Braking and traction commands may be issued to the remote locomotives via a communication link responsive to an operator using the controls at the lead locomotive. The communication link may include a wireless link between the lead locomotive and the remote locomotives maintained by the communication system.
A conventional communications linking procedure is established for setting up train communications between a lead locomotive and one or more remote locomotives for distributed power operation. Each locomotive is assigned to a respective railroad and transmits signals over the communication link using a respective radio version code, based on its respective railroad. Additionally, each locomotive is assigned a respective number identifier or road number, to distinguish it from other locomotives within the respective railroad. A link command signal is transmitted from the lead locomotive, which includes the radio version code of the lead locomotive, the number identifier of the lead locomotive, and the number identifier of the remote locomotive to which the lead locomotive intends to establish a communications link. Subsequent to receiving the link command signal, the remote locomotive verifies that the radio version code within the link command signal matches its own radio version code, that the number identifier of the remote locomotive within the link command signal matches its own number identifier, and that the number identifier of the lead locomotive within the link command signal matches an expected number identifier of the lead locomotive. If these comparisons are valid, the remote locomotive transmits a link reply signal to establish the communications link.
In the conventional procedure, since the radio version code of the lead and remote locomotive must match in order to establish the communications link, the lead and remote locomotive must belong to a common railroad. However, this introduces a noticeable drawback, as it prevents lead and remote locomotives from different railroads with different version codes from establishing a distributed power communications link. A solution was proposed to address this drawback, which creates a new radio version code that encompasses the two or more railroads between which the communications link is to be established. Thus, the remote locomotive would recognize the common radio version code in the link command signal. However, this proposed solution also introduces several drawbacks, as establishing a communications link between locomotives from two or more railroads will inherently involve the possibility of a lead and a remote locomotive having duplicate number identifiers. The proposed solution does not account for potential safety hazards introduced by this scenario. For example, if a lead and remote locomotive from different railroads have the same number identifier, the proposed solution includes a safety interlock to prohibit any communication link between these locomotives, and thus reduces its application scope. Additionally, for example, if a lead locomotive attempts to link to a first remote locomotive, while a nearby second remote locomotive has the same number identifier as the first remote locomotive, both remote locomotives may establish a communication link with the lead locomotive, based on the comparison of the common number identifier in the link command signal with their respective number identifier. Thus, the second remote locomotive may unintentionally respond to command signals from the lead locomotive after the communications link has been established, such as an emergency brake application signal, even though the second remote locomotive is located on a different train than the lead locomotive.
Heretofore, when a lead locomotive attempts to establish a communications link with one or more remote locomotive(s), conventional systems have prohibited a communications link among locomotives from different railroads. Additionally, a proposed solution to permit such communications link among locomotives from different railroads poses several drawbacks and safety risks, as the communications link procedure merely considers the number identifier, and not the particular railroad to which each locomotive belongs. It would be advantageous to provide a system that introduces a communications linking procedure that permits locomotives from different railroads to establish a communication link, while reducing these noted drawbacks.